Implementing high-speed signaling via dedicated printed circuit-board media

ABSTRACT

Some embodiments of the inventive subject matter are directed to a first circuit board configured to include an electronic component. The electronic component includes a plurality of leads. The first circuit board includes first wires configured to connect to a first portion of the plurality of leads. The second circuit board is affixed to the first circuit board. The second circuit board includes second wires. The second circuit board is smaller in size than the first circuit board. A plurality of electrical connectors extend through a thickness of the first circuit board and are configured to connect a second portion of the plurality of leads to the second wires.

BACKGROUND

Embodiments of the inventive subject matter generally relate to thefield of high-speed signaling and circuit boards, and, moreparticularly, to high-speed signaling via multiple circuit boards.

Printed circuit boards (PCBs) include electronic components (e.g.,processor chips, memory modules, etc.) with multiple input and outputleads. The multiple leads needs to be connected to other electroniccomponents, such as other processor chips, via wiring, or conductivewires, that are formed onto the PCB. Some PCBs, or portions of PCBs, mayhave a dense amount of wires connecting a dense amount of leads formultiple electronic components. For example, some PCBs include multipleprocessors that connect to each other. Each of the processors needs tocommunicate with each other, usually at very high speeds. However,because the PCB includes multiple processors, the placement of theprocessors, and their spatial configurations on the PCB, createchallenges in connecting the wires for the processors together on thePCB. One such challenge is that the spatial configuration of the wiresbecomes very crowded when many electronic components need to beconnected. The crowded wires produce background noise or cross-talk thatinterferes with each other's signals. Another challenge is that becauseof the limited space for the wires, the wires need to be very small. Thesmall size of the wires results in signal attenuation quickly over onlya short distance.

Some PCB designers have developed specific configurations for wires on aPCB. Some conventional configurations can, at best, provide high-speed,single-ended signaling at only very short distances (2-3 inches). Whenthe wires increase in length beyond the short distances cross-talk andsignal attenuation significantly interfere with signals on the wires.Thus, as designers place more electronic components on a PCB that needto communicate with each other, PCB designers are faced withincreasingly significant challenges for connecting the electroniccomponents over longer distances.

SUMMARY

Some embodiments include an apparatus with a first circuit boardconfigured to include an electronic component. The electronic componentincludes a plurality of leads. The first circuit board includes firstwires configured to connect to a first portion of the plurality ofleads. The apparatus further includes a second circuit board affixed tothe first circuit board. The second circuit board includes second wires.The second circuit board is smaller in size than the first circuitboard. The apparatus further includes a plurality of electricalconnectors that extend through a thickness of the first circuit boardand are configured to connect a second portion of the plurality of leadsto the second wires.

Some embodiments include a method directed to forming a first pluralityof pins on a first circuit board, where the first plurality of pins areconfigured to connect to a first plurality of leads of a firstelectronic component. The method can further be directed to forming asecond plurality of pins on the first circuit board. The secondplurality of pins are configured to connect to a second plurality ofleads of a second electronic component. The method can further bedirected to affixing the first circuit board to a second circuit board.The first circuit board includes a first layer configured with firstwires. The second circuit board includes a second layer configured forforming circuitry. The second circuit board is smaller in size than thefirst circuit board. For example, the second layer of the second circuitboard is limited in length to approximately a distance between the firstelectronic component and the second electronic component. The method canfurther be directed to forming second wires on the second layer of thesecond circuit board. The forming of the second wires creates anelectrical connection on the second circuit board between a portion ofthe first plurality of pins and a portion of the second plurality ofpins.

Some embodiments include an apparatus directed to a first circuit boardconfigured to include a first electronic component and a secondelectronic component. The first circuit board includes a plurality ofpins associated with a plurality of leads for the first electroniccomponent. The first circuit board includes a first layer on which firstwires are formed. The first wires connect to a first portion of theplurality of pins. The apparatus further includes a second circuit boardaffixed to the first circuit board. The second circuit board includes asecond layer on which second wires are formed. The second circuit boardis limited in size to approximately a distance between the firstelectronic component and the second electronic component. The apparatusfurther includes a plurality of electrical connectors that extendthrough a thickness of the first circuit board and connect a secondportion of the plurality of pins to the second wiring on the secondlayer.

Some embodiments are directed to a printed circuit board assembly forsingle ended signaling. The printed circuit board assembly includes afirst electronic components configured to communicate with each other atsignal speeds greater than or equal to approximately 5 Gigabits persecond. The printed circuit board assembly further includes a firstprinted circuit board to which the first electronic components areattached. The first printed circuit board has a first set of wires thatconnect the first electronic components to second electronic componentsalso attached to the first printed circuit board. The printed circuitboard assembly further includes a second printed circuit board affixedto the first printed circuit board to which the first electroniccomponents are attached. The second printed circuit board is dedicatedto connecting the first electronic components via a second set of wiresformed on the second printed circuit board. The second printed circuitboard is smaller than the first printed circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS

The present embodiments may be better understood, and numerous objects,features, and advantages made apparent to those skilled in the art byreferencing the accompanying drawings.

FIGS. 1A-1C are example conceptual diagrams of a printed circuit boardassembly using a dedicated printed circuit board media for high-speedsignaling, according to some embodiments.

FIG. 2 is an example conceptual diagram of a wiring configurationaccording to some embodiments.

FIG. 3 is an example conceptual diagram of a printed circuit boardassembly (PCBA) 300 according to some embodiments.

FIG. 4 is an example conceptual diagram of a PCBA 400 according to someembodiments.

FIG. 5 is an example conceptual diagram of a PCBA 500 according to someembodiments.

FIG. 6 is an example conceptual diagram of a PCBA 600 according to someembodiments.

FIG. 7 is an example conceptual diagram of a PCBA 700 according to someembodiments.

FIG. 8 is a flowchart depicting example operations for forming a PCBstructure according to some embodiments.

FIG. 9 depicts an example computer system 900.

FIGS. 10A and 10B illustrate graphs showing comparison results between aconventional circuit board configuration (FIG. 10A) and a circuit boardconfiguration according to some embodiments (FIG. 10B).

DESCRIPTION OF EMBODIMENT(S)

The description that follows includes exemplary systems, methods,techniques, instruction sequences, and computer program products thatembody techniques of the present inventive subject matter. However, itis understood that the described embodiments may be practiced withoutthese specific details. For instance, although examples refer to printedcircuit boards, other instances may include printed wiring boards,etched wiring board, some combinations therefore, or other forms ofmedia for connecting electronic components together, etc. In anotherinstance, although some examples refer to single-ended type signaling,other instances may include differential type signaling. In otherinstances, well-known instruction instances, protocols, structures, andtechniques have not been shown in detail in order not to obfuscate thedescription.

Some embodiments of the inventive subject matter include configurationsof wires on a PCB over longer distances (e.g., up to approximately 30inches or more, ranging between approximately 5 to 30 inches or more,etc.), that transmit signals at high frequencies and high speeds, withlimited cross-talk and limited attenuation of the signals over thewires. FIGS. 1A-1C illustrate one example according to some embodiments.

FIGS. 1A-1C are example conceptual diagrams of a printed circuit boardassembly using a dedicated printed circuit board media for high-speedsignaling, according to some embodiments. FIG. 1A is a top view of aprinted circuit board assembly (PCBA) 100. FIG. 1B is a side, cut-awayview of the PCBA 100. FIG. 1C is a three-dimensional perspective topview of the PCBA 100. The PCBA 100 includes a first circuit board(“first PCB”) 110 affixed to a second circuit board 120. Electroniccomponents are attached to the first PCB 110. The electronic componentscommunicate signals with each other at high speeds (e.g., atapproximately 5 Gigabits per second (Gbps) for single-ended signaling orhigher for differential signaling). The electronic components mayinclude, for example, single chip modules (SCM) 101, 102, and 103, suchas processor units. The SCMs 101, 102 and 103 may include integratedcircuits. The electronic components may also include memory units thatcommunicate directly with the SCMs 101, 102, and 103, such as dualinline memory modules (DIMMs) 114, 115, 116, 117, 118 and 119 (“DIMMs114-119”). High speed connections can also be used for optics, or otherelectronic components that need to communicate with each other at highspeeds. The PCBA 100 also includes a second printed circuit board(second PCB) 120 affixed to the first PCB 110. The first PCB 110 may bereferred to as a primary PCB. The second PCB 120 may also be referred toas a secondary PCB, a printed circuit board media, or a media board.

The PCBA 100 includes vias 140, 142, and 144 that run vertically throughthe first PCB 110 and through the second PCB 120. The vias 140, 142, and144 make electrical connection to some leads, but not all leads of theSCMs 101, 102, or 103 mounted on the surface 111 of the first PCB 110.For instance, in FIG. 1C, the vias 140 connect to leads 131 but notleads 133 of the SCM 101. The vias 140 run perpendicular to the surface111 of the first PCB 110 through the height, or thickness of the firstPCB 110 into the material of the second PCB 120. The vias 140 can alsorun through at least some portion of the material of the second PCB 120perpendicular to the surface 121 of the second PCB 120. The surface 121is oriented in an opposite direction to the surface 111. As illustratedin FIG. 1C, the vias 140 attached to the SCM 101 at leads 131 terminateat connector pins 141, such as on the surface 121 of the second PCB 120.In some embodiments, the first PCB 110 and/or the second PCB 120 may bea multi-layered PCBs, where wiring can be formed on one or more of thelayers of the first PCB and/or the second PCB 120. However, for sake ofbrevity, to simplify the description, FIG. 1, and other figuresdescribes below, will appear to illustrate wiring on only one layer ofthe PCB 110 and the PCB 120. The connector pins 141 are part of a pinfield 151, or grouping of conductive (e.g., metal) pins or pads to whichwires 126 are connected.

The wires 126 (also referred to as traces, or tracks), run along thesurface 121 of the second PCB 120 until connecting with additional pins(e.g., pins associated with SCMs 102 or 103) on the surface 121 of thesecond PCB 120. The additional pins are connected to the vias 142 and/or144 for the SCMs 102 and/or 103.

The second PCB 120 is dedicated only to the connections between thehigh-speed components, such as the connections made by the wires 126.The second PCB 120 has a configuration that is smaller than the firstPCB 110 and is large enough to place and route the wires 126 required toconnect the pins 141 to the additional pins associated with the SCMs 102and 103. The size of the second PCB 120 can be reduced to the size ofthe pin fields for the SCMs 101, 102, and 103, on the surface 121, plusthe size of the wires 126 as long as the wires 126 have enough space totransmit signals over long distances (e.g., up to approximately 30inches or more, between approximately 5-30 inches or more, etc.) at highspeeds (e.g., at approximately 5 Gbps or more for single endedsignaling) with minimal cross-talk and signal loss. However, because thesize of the second PCB 120 is much smaller than the first PCB 110 and isonly dedicated to connections made between high-speed electroniccomponents (e.g., via the wires 126), the second PCB 120 does notrequire a substantial amount of board material. Thus, the board materialcan utilize exotic dielectric materials with a low dielectric constantand a low dielectric dissipation factor configured for high-frequencycommunications, such as Megtron6™, Nelco®, or Teflon®, for the secondPCB 120. Further, because the second PCB 120 is dedicated only toconnection between high-speed electronic components, the second PCB 120can be tuned for wire widths and spacing that achieve a tolerable signalloss and favorable signal-to-crosstalk (S/Xt) value without affectingthe configurations (e.g., placement, line spacing, widths, routing,etc.) of other line connectors for other electronic components on thefirst PCB 110.

FIG. 2 is an example conceptual diagram of a wiring configurationaccording to some embodiments. FIG. 2 illustrates a bottom view of theportion of the PCBA 100 shown in FIG. 1C. In FIG. 2, as stated above,some of the leads or pins associated with the SCM 101 make electricalconnection through vias 140 at the surface 121 of the second PCB 120. Asstated previously, for sake of simplicity vias 140 are shown to extendthrough the second PCB 120 to the surface 121, however, in otherembodiments, the depth of vias may extend to a further or lesser extentinto the second PCB 120 depending on the number of layers of the secondPCB 120. The vias 140 connect to one or more of the pins 141 on the pinfield 151. The pin field 151 has two types of pins, signal pins andreference pins (e.g., a power or ground). The pins can be configured tohave a one-to-one ratio of signal pins to reference pins. . The pins141, thus, can have a one to one (1:1) signal-to-reference (S/R)configuration. The 1:1 S/R pin configuration may also be referred tomore succinctly as a one-to-one configuration. The pins 141, forexample, are connected via any one of the vias 140 to a signal bus forthe SCM 101.

As described previously, vias 140 only connect to some of the leads 131of the SCM 101 (i.e., the leads 133 that do not connect to the vias 140are instead routed onto the surface 111 of the first PCB 110 via wires136 or to one or more other layers of the first PCB 110). Thus the pinfield 151 is sparse and results in an enhanced escape and routingdensity. The escape and routing density is how easily the wires 126 canescape from the pin field 151. Because the pin field 151 is less densethan it would be if all of the wires were on the first PCB 110, then theescape and routing density improves by splitting up the amount of wiresbetween electronic components into two boards, the first PCB 110 and thesecond PCB 120. Consequently, the configuration of the wires 126 on thesecond PCB 120 can collapse more quickly (see the area 212 which shows aimmediate collapsing of wires 126 into a length-wise configuration onthe second PCB 120 which is made possible because the pin field 151 issparse and because routing on the media is dedicated solely toconnections between high-speed electronic components such as via wires126 on the second PCB 120).

Further, the second PCB 120 is dedicated only to connections betweenhigh-speed components, such as the SCMs 101, 102, an 103. As a result,the second PCB 120 has extra space that can be used for routing of thewires 126. Thus, the widths of the wires 126 can be wider thanconventional wire widths because of the extra space on the second PCB120. The wires 126, therefore, experience much less signal loss. Thewires 126 can also be spaced out more than conventional spacing, alsobecause of the extra space on the second PCB 120. The wires 126,therefore experience much less cross-talk and, therefore, greatersignal-to-crosstalk ratios (S/Xt) than conventional configurations. Forexample, the configuration shown in FIG. 2 can produce an S/Xt ofapproximately 18.2 dB for single ended signaling at approximately 5 Gbpsat 2.5 GHz. A conventional single-ended signaling type configuration atapproximately SGpbs at 2.5 GHz results in an S/Xt of approximately 11.7dB. The configuration of FIG. 2, thus, represents over a 50% improvementto the conventional configuration. For single ended signaling, toachieve a 5 Gbps signal speed, over a distance of approximately 30inches, the signal loss through the wires 126 (“thru loss”) should be inthe range of −10 dB to −12 db. However, conventional configurations arebeyond the range −10 dB to −12 dB range at 5 Gbps at 2.5 GHz. Further,because some embodiments of the invention can provide a high S/Xt ofapproximately 18.2 dB (e.g., at 5 Gbps for single ended signaling),embodiments provide a sufficiently high S/Xt for cyclic redundancy check(CRC) applications and single error connection double error detection(SECDED), which respectively require an S/Xt of approximately 17 dB.FIGS. 10A and 10B are illustrations of graphs showing experimentalresults. FIG. 10A illustrates an example graph 1001 that shows resultsfrom a conventional wiring configuration. The line 1002 represents adegree of thru loss. The line 1004 represents a degree of cross talk.According to the results in FIG. 10A, S/Xt is limited to approximately11.7 dB at 2.5 GH, which is insufficient to run single ended signalingat 5 Gbps. FIG. 10B, on the other hand, illustrates an example graph1010 that shows results from an embodiment of the invention configuredfor single-ended signaling. In FIG. 10B, the line 1012 represents adegree of thru loss and the line 1014 represents a degree of cross talk.According to the results in FIG. 10B, a single-ended channel, accordingto some embodiments, results in an S/Xt of 18 dB.

FIG. 3 is an example conceptual diagram of a PCBA 300 according to someembodiments. In FIG. 3, the PCBA 300 includes a first PCB 310 affixed toa second PCB 320. The second PCB 320 is smaller than the first PCB 310as similarly described above. Electronic components (e.g., SCMs 301, 302and 303, and memory modules 314, 315, 316, 317, and 318) are attached tothe first PCB 310 (shown as dashed lines to represent that theelectronic components are on a surface of the PCBA 300 opposite to asurface 321 on the second PCB 320). The second PCB 320 includes pinfields 351, 352, and 353, which include pins that connect, via athickness of the first PCB 310, to some leads from the SCMs 301, 302,and 303. The pin fields 351, 352, and 353 are approximately equivalentin surface area size to the sizes of surface areas for the SCMs 301, 302and 301. The second PCB 320 also includes pin fields 354, 355, 356, 357,358 and 359 that connect, through the thickness of the first PCB 310, toleads for the memory modules 314, 315, 316, 317, 318 and 319. The sizeof the second PCB 320 (e.g., a surface area comprising a length 381multiplied by and a width 380) is large enough to connect the pin fields351, 352, 353, 354, 355, 356, 357, 358 and 359 via wires formed (e.g.,etched) onto the surface 321 of the second PCB 320.

FIG. 4 is an example conceptual diagram of a PCBA 400 according to someembodiments. In FIG. 4, the PCBA 400 includes a first PCB 410 affixed toa second PCB 420. The second PCB 420 is smaller than the first PCB 410as similarly described above. Electronic components (e.g., SCMs 401, 402and 403, and memory modules 414, 415, 416, 417, and 418) are attached tothe first PCB 410 (shown as dashed lines to represent that theelectronic components are on surface of the PCBA 400 opposite to asurface 421 of the second PCB 420). The second PCB 420 includes pinfields 451, 452, and 453, which include pins that connect, via athickness of the first PCB 410, to some leads from the SCMs 401, 402,and 403. A size (e.g., a surface area comprising a length 481 multipliedby a width 480) of the second PCB 420 is large enough to connect the pinfields 451, 452, 453, via wires formed (e.g., etched) onto the surface421 of the second PCB 420. However, the size of the second PCB 420 isactually smaller than a surface area that comprises the three SCMs 401,402, and 403 (e.g., a length 486 multiplied by a width 486). The size ofthe second PCB 420 can be very small because the pin fields 451, 452,and 453, are much smaller in surface area size than the sizes of surfaceareas for the SCMs 401, 402 and 403. Only leads near the center of theSCMs 401, 402, and 403 extend (e.g., through vias) from the first PCB410 through to the second PCB 420.

FIG. 5 is an example conceptual diagram of a PCBA 500 according to someembodiments. In FIG. 5, the PCBA 500 includes a first PCB 510 affixed toa second PCB 520. The second PCB 520 is smaller than the first PCB 510as similarly described above. Example electronic components (e.g., anSCM 501 and a memory module 514) are attached to the first PCB 510(shown as dashed lines to represent that the electronic components areon surface of the PCBA 500 opposite to a surface 521 of the second PCB520). The second PCB 520 includes a pin field 551 which includes pinsthat connect, via a thickness of the first PCB 510, to some leads fromthe SCMs 501. A second pin field 554 includes pins that connect, via thethickness of the first PCB 510, to some leads from the memory module514. The second PCB 520 is an irregular shape having a bridge 590 thatconnects a first portion 591 of the second PCB 520 to a second portion592 of the second PCB 520. The portion 591 and 592 include the pinfields 551 and 554. The portions 590 and 591 include wires that connectthe pin fields 551 and 554 via the bridge 590. The bridge 590 is smallerthan the first portion 591 and utilizes a small enough amount of boardmaterial to include only the wires needed to connect the pin field 554to the pin field 551, but still permits the wires to have enough spaceand wire width as similarly described above.

FIG. 6 is an example conceptual diagram of a PCBA 600 according to someembodiments. In FIG. 6, the PCBA 600 includes a first PCB 610 affixed toa second PCB 620. The second PCB 620 is smaller than the first PCB 610as similarly described above. Example electronic components (e.g., SCMs601, 602, 603, and 604 and memory module 612, 613, 614, 615, 616, 617,618, and 619) are attached to the first PCB 610. The second PCB 620 isshown as a dashed line to represent that the second PCB 620 is oppositeto a surface 611 of the first PCB 610. The SCMs 601, 602, 603 and 604are arranged in a matrix form. The matrix form is a differentconfiguration from an inline form demonstrated by the arrangement of theSCMs 101, 102, and 103 in FIGS. 1A, 1B, 3 and 4. In FIG. 6, the secondPCB 610 has a shape that conforms to the arrangement of the SCMs 601,602, 603 and 604.

FIG. 7 is an example conceptual diagram of a PCBA 700 according to someembodiments. The PCBA 700 includes many similar elements as the PCBA 100in FIGS. 1A-1C. In FIGS. 1A-1C, however, the second PCB 120 is connecteddirectly to the underside surface of the first PCB 120, such as by alamination process, so that there is no space between the first PCB 110and the second PCB 120. In FIG. 7, however, a first PCB 710 is connectedto a second PCB 720 via land grid array (LGA) connectors 740. A firstsurface 711 of the first PCB 710 can include attached electroniccomponents, such as SCMs 701, 702, and 703 and memory modules 714, 716,and 718. A second surface 721 of the second PCB 720 can include wiringthat extends from the LGA connectors across the second PCB 720 tointerconnect the LGA connectors 740. The PCBA 700 includes vias thatextend through a thickness of the first PCB 710 to connect a portion ofthe leads from the SCMs 701, 702, and 703 to pins on the LGA connectors740. In some embodiments, the PCBA 700 can further include vias thatextend through some or all of the thickness of the second PCB 720.

FIG. 8 is a flowchart depicting example operations for forming a PCBstructure according to some embodiments. For exemplary purposes,operations associated with the blocks in FIG. 8 will be described asbeing performed by a PCB fabrication system (“system”), which may, forexample, include any or all of the elements described in FIGS. 1A-1C, 2,3, 4, 5, 6, 7, and 9. FIG. 8 illustrates a flow that the system canperform.

Referring to FIG. 8, the system forms first pins on a first surface of afirst circuit board (802). The first pins are configured to connect toleads of a first electronic component.

Further, the system forms second pins on the first circuit board (804).The second pins are configured to connect to leads of a secondelectronic component. The second pins are, in some embodiments up toapproximately 30 inches in length away from the first pins.

Further, the system affixes a second circuit board to an underside ofthe first circuit board where the second circuit board spans the up toapproximately 30 inches in length and is smaller in size than the firstcircuit board (806). The first circuit board includes a first surfaceconfigured with first wires. The second circuit board includes a secondsurface configured for forming circuitry. For example, the secondcircuit board can be coated with a metallic material (e.g., copper) fromwhich copper-wire circuitry can be formed. The second surface of thesecond circuit board can be limited in size (e.g., length, width, etc.)to be approximately a size (e.g., length, width, etc.) of an area on thefirst surface that includes the first electronic component and thesecond electronic component. For instance, a length of the secondcircuit board can be approximately the size of a distance between thefirst electronic component and the second electronic component if thefirst electronic component and the second electronic component are thefurthest units in a group of electronic units that need to be connected,and communicate at high speeds, via second wires formed on the secondcircuit board. The distance between the first electronic component andthe second electronic component can be beyond conventional distances(e.g., beyond the 2-3 inches between electronic components of someconventional type configurations). For example, as stated above, thedistance between the first electronic component and the secondelectronic component can be as far apart, in some embodiments, asapproximately 30 inches. In some embodiments, the first circuit boardincludes a third surface opposite and perpendicular to the firstsurface, and the second circuit board includes a fourth surface oppositeand perpendicular to the second surface. The system can laminate thethird surface of the first circuit board to the fourth surface of thesecond circuit board.

Further, the system forms second wires on a second surface of the secondcircuit board to create an electrical connection on the second circuitboard between a portion of the first pins and a portion of the secondpins, where the second wires are spaced sufficiently to communicate atsignal speeds of greater than or equal to approximately 5 Gbps withoutsignificant cross-talk or significant signal loss (808). In someembodiments, the system can form the second wires to have wire widthssufficient to limit signal attenuation to less than or equal to 12decibels over the up to approximately 30 inches in distance between thefirst electronic component and the second electronic component forsignal communications greater than or equal to the approximately 5 Gbps.Further, the system can space the second wires on a layer of the secondcircuit board to have a signal-to-cross-talk ratio of greater than 17decibels for signal communications greater than or equal to theapproximately 5 Gbps.

In some embodiments, the system can form first vias configured toconnect the portion of the first pins to third pins on the secondsurface of the second circuit board. The system can further form secondvias configured to connect the portion of the second pins to fourth pinsalso on the second surface of the second circuit board. In someembodiments, the first vias and second vias can extend, at least,through a thickness of the first circuit board. In some embodiments, thefirst vias and second vias can also extend through a thickness of thesecond circuit board. The system can further connect the third pins tothe fourth pins via the second wires. In some embodiments, the systemcan attach the first wires to create an electrical connection between asecond portion of the first pins and a second portion of the second pinsvia the first surface of the first circuit board. The second portion ofthe first pins and the second portion of the second pins can beexclusive of the first portion of the first pins and the second portionof the second pins. In other words, in some embodiments, the systemconnects some of the pins for the first and second electronic componentson the first circuit board and some of the pins (e.g., different pins)for the first and second electronic components on the second circuitboard.

FIG. 9 depicts an example computer system 900. The computer system 900includes a processor unit 901 (possibly including multiple processors,multiple cores, multiple nodes, and/or implementing multi-threading,etc.). The computer system 900 includes memory 907. The memory 907 maybe system memory (e.g., one or more of cache, SRAM, DRAM, zero capacitorRAM, Twin Transistor RAM, eDRAM, EDO RAM, DDR RAM, EEPROM, NRAM, RRAM,SONOS, PRAM, etc.) or any one or more of the above already describedpossible realizations of machine-readable or computer readable media.The computer system 900 also includes a bus 903 (e.g., PCI bus, ISA,PCI-Express bus, HyperTransport® bus, InfiniBand® bus, NuBus bus, etc.),a network interface 905 (e.g., an ATM interface, an Ethernet interface,a Frame Relay interface, SONET interface, wireless interface, etc.), anda storage device(s) 909 (e.g., optical storage, magnetic storage, etc.).The computer system 900 also includes circuit board formation module921. The circuit board formation module 921 can control formation (e.g.,design, simulation, test, layout, manufacture, etc.) of circuit boardson which integrated circuit chips may be connected according to someembodiments. The circuit board design controller 921 can includeindividual components or parts that manage different aspects or parts ofthe circuit board formation Any one of these functionalities may bepartially (or entirely) implemented in hardware and/or on the processingunit 901. For example, the functionality may be implemented with anapplication specific integrated circuit, in logic implemented in theprocessing unit 901, in a co-processor on a peripheral device or card,etc. Further, realizations may include fewer or additional componentsnot illustrated in FIG. 9 (e.g., video cards, audio cards, additionalnetwork interfaces, peripheral devices, etc.). The processor unit 901,the storage device(s) 909, and the network interface 905 are coupled tothe bus 903. Although illustrated as being coupled to the bus 903, thememory 907 may be coupled to the processor unit 901.

The computer system described above and the method described in the flowabove may be used in a design, simulation, test, layout, and manufactureof circuit boards on which integrated circuit chips may be connectedaccording to some embodiments. The method may include includesprocesses, machines and/or mechanisms for processing design structuresor devices to generate logically or otherwise functionally equivalentrepresentations of structures and/or devices described above and shownin FIGS. 1A-1C, 2, 3, 4, 5, 6 and 7. The design structures processedand/or generated may be encoded on machine-readable transmission orstorage media to include data and/or instructions that when executed orotherwise processed on a data processing system generate a logically,structurally, mechanically, or otherwise functionally equivalentrepresentation of hardware components, circuits, devices, or systems.Machines include, but are not limited to, any machine used in a circuitboard design process, such as designing, manufacturing, or simulating acircuit board, a circuit board component, a circuit board device, orcircuit board system. For example, machines may include machines and/orequipment for generating masks, computers or equipment for simulatingdesign structures, any apparatus used in the manufacturing or testprocess, or any machines for programming functionally equivalentrepresentations of the design structures into any medium (e.g. a machinefor programming a programmable gate array). Design structures mayinclude an input design structure and/or a logical simulation designstructure. Design structures may also or alternatively comprise dataand/or program instructions that when processed generate a functionalrepresentation of the physical structure of a circuit board, a portionof a circuit board, and/or hardware devices on the circuit board.Whether representing functional and/or structural design features, adesign structure may be generated using electronic computer-aided design(ECAD) such as implemented by a core developer/designer. When encoded ona machine-readable data transmission, gate array, or storage medium, adesign structure may be accessed and processed by one or more hardwareand/or software modules within a design process to simulate or otherwisefunctionally represent a printed circuit board assembly, an electroniccomponent on a printed circuit board, a circuit formed on or associatedwith the circuit board, electronic or logic modules, apparatus, device,or system such as those shown above. As such, a design structure maycomprise files or other data structures including human and/ormachine-readable source code, compiled structures, andcomputer-executable code structures that when processed by a design orsimulation data processing system, functionally simulate or otherwiserepresent circuits or other levels of hardware logic design. Such datastructures may include hardware-description language (HDL) designentities or other data structures conforming to and/or compatible withlower-level HDL design languages such as Verilog and VHDL, and/or higherlevel design languages such as C or C++.

A design process can employ and incorporate hardware and/or softwaremodules for synthesizing, translating, or otherwise processing adesign/simulation functional equivalent of the components, circuits,devices, or structures shown above to generate a file which may containdesign structures. The file may comprise, for example, compiled orotherwise processed data structures representing a list of wires,discrete components, models, etc. that describe the connections to otherelements and circuits in a circuit board design. The file may besynthesized using an iterative process in which the file isresynthesized one or more times depending on design specifications andparameters for the device. As with other design structure typesdescribed herein, the file may be recorded on a machine-readable datastorage medium or programmed into a programmable gate array. The mediummay be a non-volatile storage medium such as a magnetic or optical diskdrive, a programmable gate array, a compact flash, or other flashmemory. Additionally, or in the alternative, the medium may be a systemor cache memory, buffer space, or electrically or optically conductivedevices and materials on which data packets may be transmitted andintermediately stored via the Internet, or other networking suitablemeans.

A design process may include hardware and software modules forprocessing a variety of input data structure types. Such data structuretypes may reside, for example, within library elements and include a setof commonly used elements, circuits, and devices, including models,layouts, and symbolic representations, for a given manufacturingtechnology. The data structure types may further include designspecifications, characterization data, verification data, design rules,and test data files which may include input test patterns, output testresults, and other testing information. A design process may furtherinclude, for example, standard mechanical design processes such asstress analysis, thermal analysis, mechanical event simulation, processsimulation for operations such as casting, molding, etc. One of ordinaryskill in the art of mechanical design can appreciate the extent ofpossible mechanical design tools and applications used in a designprocess without deviating from the scope and spirit of the embodimentsof the inventive subject matter described. A design process may alsoinclude modules for performing standard design processes such as timinganalysis, verification, design rule checking, place and routeoperations, etc.

A design process may employ and incorporate logic and physical designtools such as HDL compilers and simulation model build tools to processa design structure together with some or all of the depicted supportingdata structures along with any additional mechanical design or data (ifapplicable), to generate additional design structures that reside on astorage medium or programmable gate array in a data format used for theexchange of data of mechanical devices and structures (e.g. informationstored in a IGES, DXF, Parasolid XT, JT, DRG, or any other suitableformat for storing or rendering such mechanical design structures). Theadditional design structures can comprises one or more files, datastructures, or other computer-encoded data or instructions that resideon transmission or data storage media and that when processed by an ECADsystem generate a logically or otherwise functionally equivalent form ofone or more of the embodiments of the invention shown in FIGS. 1A-1C, 2,3, 4, 5, 6, and 7. In one embodiment, a design structure may comprise acompiled, executable HDL simulation model that functionally simulatesthe devices shown above.

A design structure may also employ a data format used for the exchangeof layout data of circuit boards and/or symbolic data format. A designstructure may comprise information such as, for example, symbolic data,map files, test data files, design content files, manufacturing data,layout parameters, wires, levels of metal, vias, shapes, data forrouting through the manufacturing line, and any other data required by amanufacturer or other designer/developer to produce a device orstructure as described above and shown in figures above. A designstructure may be transferred amongst different entities involved indesigning and/or manufacturing.

As will be appreciated by one skilled in the art, aspects of the presentinventive subject matter may be embodied as a system, method or computerprogram product. Accordingly, aspects of the present inventive subjectmatter may take the form of an entirely hardware embodiment, an entirelysoftware embodiment (including firmware, resident software, micro-code,etc.) or an embodiment combining software and hardware aspects that mayall generally be referred to herein as a “circuit,” “module” or“system.” Furthermore, aspects of the present inventive subject mattermay take the form of a computer program product embodied in one or morecomputer readable medium(s) having computer readable program codeembodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium may be any tangible medium that can contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent inventive subject matter may be written in any combination ofone or more programming languages, including an object orientedprogramming language such as Java, Smalltalk, C++ or the like andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The program codemay execute entirely on the user's computer, partly on the user'scomputer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through any type of network, includinga local area network (LAN) or a wide area network (WAN), or theconnection may be made to an external computer (for example, through theInternet using an Internet Service Provider).

Aspects of the present inventive subject matter are described withreference to flowchart illustrations and/or block diagrams of methods,apparatus (systems) and computer program products according toembodiments of the inventive subject matter. It will be understood thateach block of the flowchart illustrations and/or block diagrams, andcombinations of blocks in the flowchart illustrations and/or blockdiagrams, can be implemented by computer program instructions. Thesecomputer program instructions may be provided to a processor of ageneral purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer orother programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

While the embodiments are described with reference to variousimplementations and exploitations, it will be understood that theseembodiments are illustrative and that the scope of the inventive subjectmatter is not limited to them. In general, techniques for formingcircuit boards and circuit board assemblies as described herein may beimplemented with facilities consistent with any hardware system orhardware systems. Many variations, modifications, additions, andimprovements are possible.

Plural instances may be provided for components, operations, orstructures described herein as a single instance. Finally, boundariesbetween various components, operations, and data stores are somewhatarbitrary, and particular operations are illustrated in the context ofspecific illustrative configurations. Other allocations of functionalityare envisioned and may fall within the scope of the inventive subjectmatter. In general, structures and functionality presented as separatecomponents in the exemplary configurations may be implemented as acombined structure or component. Similarly, structures and functionalitypresented as a single component may be implemented as separatecomponents. These and other variations, modifications, additions, andimprovements may fall within the scope of the inventive subject matter.

What is claimed is:
 1. An apparatus comprising: a first circuit boardconfigured to include an electronic component, said electronic componentincluding a plurality of leads, said first circuit board including firstwires configured to connect to a first portion of the plurality ofleads; a second circuit board affixed to the first circuit board, saidsecond circuit board including second wires, said second circuit boardbeing smaller in size than the first circuit board; and a plurality ofelectrical connectors that extend through a thickness of the firstcircuit board, said plurality of electrical connectors configured toconnect a second portion of the plurality of leads to the second wires,wherein the first circuit board is further configured to include anadditional electronic component, wherein the second circuit board islimited in size to approximately a distance between the electroniccomponent and the additional electronic component, wherein the distancebetween the electronic component and the additional electronic componentis between approximately 5 inches to approximately 30 inches, andwherein the second wires include a spatial configuration on the secondcircuit board that has a signal-to-cross talk ratio of greater than 17decibels for signal communications at greater than or equal toapproximately 5 Gigabits per second for single ended signaling.
 2. Theapparatus of claim 1, wherein the second wires have wire widthssufficient to limit signal attenuation on the second wires to less thanor equal to 12 decibels over the distance for said signal communicationsat greater than or equal to approximately 5 Gigabits per second forsingle ended signaling.
 3. The apparatus of claim 1, wherein saidadditional electronic component includes an additional plurality ofleads, said first wires connecting to a first portion of the additionalplurality of leads, and said second wires further configured to connecta second portion of the additional plurality of leads via an additionalplurality of electrical connectors that extend through the thickness ofthe first circuit board.
 4. The apparatus of claim 1, wherein the firstcircuit board is laminated to the second circuit board.
 5. The apparatusof claim 1, wherein the plurality of electrical connectors are one ormore of vias and land-grid array connectors.
 6. The apparatus of claim1, wherein the second circuit board includes connections between onlyhigh speed electronic components, and wherein the size of the secondcircuit board is configured for widths and spacing of the second wiresto have less signal loss and lower signal-to-crosstalk values than thefirst wires on the first circuit board.
 7. The apparatus of claim 1,wherein the plurality of electrical connectors extend from the secondportion of the plurality of leads through holes in a board material ofthe first circuit board to the second wires.
 8. The apparatus of claim7, wherein the holes extend from a first surface of the first circuitboard in which the first wires are situated, through the board material,and out of a second surface of the first circuit board, wherein thethickness of the first circuit board is a distance from the firstsurface to the second surface, and wherein the holes are orientedperpendicular to both the first surface and the second surface.
 9. Anapparatus comprising: a first circuit board configured to include afirst electronic component and a second electronic component, said firstcircuit board including a plurality of pins associated with a pluralityof leads for the first electronic component, said first circuit boardincluding a first layer on which first wires are formed, and said firstwires connecting to a first portion of the plurality of pins; a secondcircuit board affixed to the first circuit board, said second circuitboard including a second layer on which second wires are formed, andsaid second circuit board being limited in size to approximately adistance between the first electronic component and the secondelectronic component; and a plurality of electrical connectors thatextend through a thickness of the first circuit board and connect asecond portion of the plurality of pins to the second wires on thesecond layer, wherein the second circuit board is smaller than the firstcircuit board, and wherein the second wires are configured to have aspatial configuration and wire width sufficient to extend up toapproximately 30 inches in length with a signal-to-cross talk ratio ofgreater than 17 decibels and a signal attenuation of less than or equalto 12 decibels for signal communications at greater than or equal toapproximately 5 Gigabits per second for single-ended signaling.
 10. Theapparatus of claim 9, wherein the second circuit board includes a secondplurality of pins to which the second portion of the plurality of pinsare connected, wherein said second plurality of pins include signal typepins and reference type pins, said signal type pins configured to carrysignals from the first electronic component and said reference type pinsconfigured as either power or ground references for the signals, andwherein the second wiring includes a one-to-one ratio of connections tothe signal type pins and the reference type pins.
 11. The apparatus ofclaim 10, wherein the first electronic component is configured tocommunicate with the second electronic component, wherein said secondwires on the second circuit board connect at least a portion of thesecond plurality of pins on the second circuit board to a thirdplurality of pins on the second circuit board, said third plurality ofpins associated with the second electronic component.
 12. The apparatusof claim 10, wherein said first electronic component and said secondelectronic component are configured to communicate at greater than equalto approximately 5 Gigabits per second at approximately 2.5 Gigahertzclock speeds.
 13. The apparatus of claim 9, wherein the second circuitboard is laminated to the first circuit board, and wherein the pluralityof electrical connectors are vias that extend through the thickness ofthe first circuit board and through at least a portion of a thickness ofthe second circuit board and connect a second portion of the pluralityof pins to the second wires on the second layer.
 14. The apparatus ofclaim 9, wherein the first electronic component is attached to the firstcircuit board, wherein a first portion of the plurality of leads areconnected to the first portion of the plurality of pins, and wherein asecond portion of the plurality of leads are connected to a secondportion of the plurality of pins.
 15. The apparatus of claim 9, whereinthe second circuit board comprises a material with a low dielectricconstant and a low dielectric dissipation factor configured forhigh-frequency communications.
 16. A printed circuit board assembly forsingle ended signaling, the printed circuit board assembly comprising:first electronic components configured to communicate with each other atsignal speeds greater than or equal to approximately 5 Gigabits persecond; a first printed circuit board to which the first electroniccomponents are attached, said first printed circuit board having a firstset of wires that connect the first electronic components to secondelectronic components also attached to the first printed circuit board;and a second printed circuit board affixed to the first printed circuitboard to which the first electronic components are attached, whereinelectrical connectors extend through the first printed circuit board andconnect the first electronic components to a second set of wires formedon the second printed circuit board, wherein the second printed circuitboard is smaller than the first printed circuit board, and wherein thesecond set of wires are configured to have a spatial configuration onthe second printed circuit board sufficient to extend up toapproximately 30 inches in distance with a signal-to-cross talk ratio ofgreater than 17 decibels and a signal attenuation of less than or equalto 12 decibels.
 17. The printed circuit board assembly of claim 16,wherein a size of the second printed circuit board is approximatelyequivalent to a combination of a first area of a surface thatencompasses the first electronic components plus a second area of thesecond printed circuit board on which the second set of wires areformed.
 18. The printed circuit board assembly of claim 16, wherein thesecond printed circuit board has a one-to-one ratio of signal toreference pins.